Ionophore-Containing Siloprene Membranes: Direct Comparison between Conventional Ion-Selective Electrodes and Silicon Nanowire-Based Field-Effect Transistors

Abstract

Siloprene-based, ion-selective membranes (ISMs) were drop-casted onto a field-effect transistor device that consisted of a single-chip array of top-down prepared silicon nanowires (SiNWs). Within one array, two sets of SiNWs were covered with ISMs, each containing two different ionophores, allowing the simultaneous sensing of K and Na ions using a flow cell. It is shown that both ions can be effectively detected in the same solution over a wide concentration range from 10(-4) to 10(-1) M without interference. The ISMs were also analyzed in a conventional ISE configuration, allowing a direct comparison. While the responses for K(+) were similar for both sensor configurations, remarkably, the Na(+) response of the ISM-covered SiNW device was found to be higher than the one of the ISE configuration. The addition of a Na(+) buffering hydrogel layer between the SiO2 of the SiNW and the ISM reduced the response, showing the importance of keeping the boundary potential at the SiO2/ISM interface constant. The responses of the siloprene-covered SiNW devices were found to be stable over a period of at least 6 weeks, showing their potential as a multichannel sensor device.

Selective layer-free blood serum ionogram based on ion-specific interactions with a nanotransistor

“…5). The error obtained here with the selective-layer-free approach was the same or smaller than errors found for ions (other than H 3 O + ) with selective-layer-based stateof-the-art nanowire 27,28 and graphene 46 transistor sensors or with a recently commercialized cheap, reusable (but not biocompatible) ion sensor for domestic purposes (see Supplementary Table 2 for a comparison with academic and commercial sensors). As the Nernst limit is usually not exceeded with selective-layer-based sensors, the 230% gain in sensitivity reported here for divalent ions strengthens the versatility of the sensor (Supplementary Note 1).…”

“…One common aspect of these issues relates to the so-called selective layer, which is designed to capture an analyte selectively. Addition of a thin organic selective layer to sense analytes other than H 3 O + disrupts the high durability and precision of metal oxide -covered miniaturized pH sensor devices 20,[26][27][28][29][30] . A fundamentally different approach would be to take advantage of non-covalent specific surface interactions to perform selective-layer-free measurements of analytes in unknown solutions with a versatile and mass-fabricationcompatible device.…”

Modeling Selectivity and Cross-sensitivity in membrane-based potentiometric sensors

“…The combination of integrated silicon FETs with ion selective membranes (ISMs) has greatly extended the application domains of potentiometric sensors [1], [2]. Such device consists of replacing the gate of a FET with an ISM in contact with the electrolyte chamber containing the target analytes (Fig.…”

Hydrosulfide-selective ChemFETs for aqueous H2S/HS− measurement

“…The key feature of our HS − selective ChemFETs is the application of a hydrosulfide-selective polymer membrane, to the silicon nitride gate oxides of commercially available pH-sensitive FETs. ChemFETs often have chemically selective membranes comprised of PVC, PDMS, and occasionally NBR among other formulations [ 22 , 26 – 29 ]. Generally, the polymers alone have limited native sensitivity to ionic targets and their sensitivity/selectivity is be imparted by incorporating chemical recognition elements (CRE) into the polymer membranes to create the interfacial chemically selective material of the device.…”

“…Activity coefficients were calculated using the Davies equation. Selectivity coefficients were determined by the Fixed Interference method according to IUPAC recommendations [ 29 ]. All uncertainties are reported as Standard Error of the Mean (SEM).…”